figures



Jan. 8, 1.963 T. L. URQUHART 3,072,394

I OPERATING SYSTEM FOR MULTI-LEAF DOORS Filed May 25, 1959 I 3 Sheets-Sheet 1 FIGJ.v

)IA/IVENTOR. THO-R TON LMRQUHART ATTORNEYS Jan. 8, 1963 1-. 1 URQUHART 3,072,394

OPERATING SYSTEM FOR MULTI-LEAF DOORS Filed May 25, 1959 5 Sheets-Sheet 2 4 H8 us 44V FIG.4.

IINVENTQR.

w THOR T L-IURQUHART \E BY 'r- Wa /M7 ATTORNEYS Jan. 8, 1963 1'. L. URQUHART 3,072,394

OPERATING SYSTEM FOR MULTI-LEAF' DOORS Filed May 25, 1959 5 Sheets-Sheet 3 FIG.6.

FIG.5.

' x I28 m F/ lll 1m 4 ATTO NEYS United States Patent 3,ti72,394 ()PERATWG SYSTEM 136R MULTI-LEAF DOORS Thornton L. Urquhart, Farmington, Mich, assignor to Byrne Doors, Inc, Ferndale, Mich, a corporation of Michigan Filed May 25, 1959, Ser. No. 815,420 2 Claims. (Cl. 268-48) The invention relates generally to door operating systems and refers morespecifically to apparatus for moving centrally divided multi-leaf sliding doors to open and closed positions including a centrally located traveling carriage having anti-friction members mounted thereon acting in cooperation with a single continuous linear member, fixed anti-friction members located on opposite sides of the multi-leaf sliding doors, and drive means for the continuous linear member to simultaneously move said doors so that they arrive at a full closed position centrally of an opening to be closed or at a full opened position on opposite sides of said opening at the same time.

In the past, relatively wide, high openings such as the entrance openings to airplane hangars, factories, Warehouses and the like, have been closed by doors formed of a plurality of leaves which were movable on guides or tracks simultaneously at ditferent rates to arrive at a fully open or fully closed position at the same time. Such doors have however been subject to the criticism that heavy operating mechanism therefor was required in the space above the doors which greatly increased the cost of the structure wherein the doors were installed, that the operating mechanisms for the doors were not sufficiently protected from dirt, snow and the like, and that the opening and closing thereof was not uniform.

Furthermore, many multi-leaf doors of the size required to close the high wide openings under consideration have in the past been attached to a single side of an opening to be closed and have been operated by means positioned at the said single side of said opening and cables attached to a plurality of idividual pulleys secured to individual leafs of said doors. Such construction necessitates the traveling of at least one leaf of the door over the full width of the opening or requires duplication of the multi-leaf doors and the operating mechanism therefor on each side of the opening so that the end leaves of a pair of doors meet in the center of the opening. The duplication of the operating means on opposite sides of the opening is of course expensive. When one leaf of the door is required to travel the full width of the opening the time required to open or close the door is often excessive. Also the operation of multi-leaf doors wtih a plurality of cables attached to a plurality of pulleys or drums or sheaves attached to individual leaves of the door multiplies the chance of malfunction of the operating mechanism.

Therefore it is one of the objects of the present invention to provide a door operating system for centrally divided multi-leaf sliding doors which is compact, light weight, uncomplicated and capable of moving all the leaves of the divided sliding doors simultaneously so that they arrive at their fully open or fully closed position at the same time.

Another object is to provide door operating apparatus for centrally divided multi-leaf sliding doors which may be economically located in a position ofiering maximum protection therefor.

Another Object is to provide door operating apparatus for centrally divided multi-leaf sliding doors which is so constructed that uniform movement of the individual door leaves is assured.

More specifically it is an object to provide door operating apparatus for centrally divided multi-leaf sliding doors including a centrally located traveling carriage having anti-friction members mounted thereon, anti-friction members fixedly secured on both sides of said doors, a single continuous linear member mounted on the antifriction members, and a single drive means for said linear member located at one side of the doors, and capable of moving all the leaves of the divided sliding doors simultaneously so that they arrive at their fully open or fully closed position at the same time.

Still more specifically it is an object of the present invention to provide door operating apparatus for centrally divided multi-leaf sliding doors including a traveling sheave carriage slidably mounted on a track over said doors, fixed sheaves at each side of said doors, a single continuous cable, the ends of which are secured at opposite sides of said doors, passing in a plurality of strands between said fixed sheaves and said traveling sheave carriage, each leaf of said doors being attached to separate strands of said cable for movement therewith and means located at one side of said doors to impart movement to the cable, whereby said door leaves are caused to simultaneously move between fully open and fully closed positions on movement of said cable and to arrive at said positions together.

These and other objects, advantages and novel details of construction of this invention will be made more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, wherein:

FIGURE 1 is a perspective view of a centrally divided multi-leaf door operating system according to the invention.

FIGURE 2 is a top view of the door operating system of FIGURE 1.

FIGURE 3 is a partial front elevation of the door operating system of FIGURE 1.

FIGURE 4 is a front elevation of a bracket used to attach the cable of the door operating system of FIGURE 1 to the individual leaves of the doors.

FIGURE 5 is a side elevation of the bracket of FIG- URE 4 taken in the direction of the arrow 5 in FIGURE 4 FIGURE 6 is a cross-section of the traveling sheave carriage of the door operating system of FIGURE 1.

FIGURE 7 is a longitudinal section of the traveling sheave carriage of the door operating system of FIGURE 1 taken on the line 77 in FIGURE 6.

One embodiment of the door operating system of the invention will now be described with particular reference to the figures of the drawing.

The door operating system of the invention generally indicated it) shown in FIGURE 1 comprises a diagrammatically illustrated sheave carriage, generally indicated 12 and centrally located with respect to a pair of centrally divided, multi-leaf doors generally indicated 28 and 3t), anti-friction members or sheaves 14, 16, 18 and 2t) rotatably mounted on the sheave carriage 12, pairs of anti-friction members or sheaves 21 and 22, and 24 and 26 secured for rotation in a fixed position at the opposite sides 29 and 31 respectively of an opening 33 in a building structure 35 which is to be closed by doors 28 and 30. A continuous linear member or cable generally indicated 32 reeved on each of the above indicated sheaves and passing therebetween in a plurality of individual strands as shown is also provided as an operating part of the door operating system of the invention. Drive means for the cable 32, generally indicated 34 is located adjacent side 29 of the building opening and is connected in driving relation to sheave 22 as shown. Brackets 36, 38, 4t) and 4-2 are provided as shown in FIGURE 1 to connect the individual leaves 44, 46, 48 and 50 respectively to individual strands of the cable 32.

With the door operating system arranged as shown in the FIGURES, the individual leaves 44, 46, 48 and 50 of the doors 28 and 38 will move simultaneously to the open position at the sides 29 and 31 of the opening 33 in the building structure 35 and arrive thereat at the same time on clockwise rotation of sheave 22 caused by drive means 34. Similarly on counter clockwise rotation of sheave 22 the doors 28 and 33 will move as shown in FIGURE 1 under the influence of the operating system 16 from an open position to the position indicated in FIGURE 1.

The doors 28 and 30 as best shown in FIGURE 1 include leaves 44 and 46, and 48 and 511, respectively. In operation the doors 28 and 30 are caused to separate centrally as shown at 51 and slide in opposite directions into conventional door pockets (not shown) in a building structure 35. In the fully opened position the leaves 44 and 46 and the leaves 48 and 50 of the doors 28 and 30 are adapted to overlap each other in the well known manner of multi-leaf sliding doors. The doors 28 and 38 are shown in FIGURE 1 in substantially their fully closed position. (Ionventional guide tracks (not shown) may be provided to guide the doors 28 and 3% in their movement between their open and closed positions in a particular installation. Likewise conventional anti-friction means may be attached to the doors 28 and 30 to facilitate their sliding movement during operation. Since the basic nature of centrally divided multi-leaf sliding doors as outlined above is well known the doors have been indicated only diagrammatically in the figures and will not be described in further detail herein.

The doors 28 and 30 shown in FIGURE 1 are vertically mounted for horizontal sliding to open and close a large opening in a building structure 35 such as an airplane hangar. According to the invention, in such an installation support and guide means 52 as best shown in FIGURE 6 must be provided for the traveling sheave carriage 12 immediately above and parallel to the doors 28 and 38. The support and guide means 52 shown in FIGURE 6 comprises an inverted structural channel member 54 having structural angle 56 and 58 attached to the downwardly extending flanges thereof by convenient means such as welding in the manner shown. The support and guide means 52 may be designed and constructed as an integral part of the building structure 35 in which the opening 33 to be closed by doors 28 and 30 is located. The support and guide means 52 will therefore add little weight to the structural frame of the building structure. Also, in the form shown, it will be noted that the support and guide member 52 substantially completely protects the traveling sheave carriage 12 from becoming clogged with dirt, snow or the like.

The traveling sheave carriage 12 as best shown in FIG- URES 6 and 7 includes a frame generally indicated 60 which may be built up of steel plate by welding in the form shown. A pair of longitudinally extending formica blocks 62 and 64 are secured to the underside of the horizontal member 66 of frame 60 by means of bolts 68 in the location shown. The blocks 62 and 64 provide a bearing contact with angle members 56 and 58 to support the carriage 12 and permit longitudinal sliding thereof within the support and guide means 52. Similar vertically extending formica blocks 72, 74, and 76 as illustrated and formica block (not shown) are symmetrically secured to the downwardly extending members 80 and 82 of frame 60 by means of bolts 84 to provide lateral guide surfaces for the carriage 12 which will allow sliding of the carriage 12 within the guide and support means 52. Spacing shims 85 are provided between the formica blocks 72, 74, 76 and 78 and the downwardly extending frame members 80 and 82 to properly space the formica blocks for sliding contact with the angle members 56 and 58.

Anti-friction members in the form of pairs of freely rotatable sheaves 14 and 16, and 18 and 21] are mounted on thrust bearings 86 and 88 respectively which are in turn mounted on pins 90 and 92 respectively which are journaled in the downwardly extending frame members and 82 as shown. Slots 94 and 96 are provided in pins and 32 respectively as shown best in FIGURE 6 to receive locking plates 98 and 100 which prevent pins 94 and 86 from rotating or moving laterally with respect to the carriage 12. The locking plates 98 and 100 are secured to the downwardly extending member 80 of frame 60 by means of bolts 102. In operation of the doors 2S and 31) on rotation of the drive means 34, the carriage 12 will be caused to slide within the guide and support means 52 a distance equal to half of the distance traveled by the slowest moving door leaves 44 and 50 as will be subsequently explained.

The sheaves 21 and 22 as shown diagrammatically at the right in FIGURE 1 are mounted on a shaft 104 as indicated. The shaft 104 must be rotatably secured to a fixed object such as the building structure 35 in a position a shown by convenient means (not shown). The sheave 21 is mounted for free rotation on shaft 104. Sheave 22 is fixedly attached to shaft 104 for rotation therewith. Sheaves 24 and 26 are mounted at the left of doors 28 and 30 on shaft 196 for free rotation thereon. Shaft 106 must also be fixedly supported for rotation by convenient means (not shown) which may be secured to the building structure.

The cable 32 as best shown in FIGURE 1 has one end thereof fixedly attached to the building structure 35 by means of a clamp 183 at the right side of doors 28 and 30 as shown in FIGURE 1. The cable 32 then passes between the clamp 168 and sheave 18 on carriage 12 in a strand 110 and is then reeved on sheave 18 in an upward direction as shown. The cable 32 then passes between the sheaves 18 and 21 in a strand 112 and is reeved over sheave 21 in a downward direction. Strand 114 of cable 32 then extends between sheave 21 and sheave 20 and cable 32 is reeved over sheave 20 in an upward direction. From sheave 20, cable 32 extends in strand 116 to sheave 22 and it is reeved therearound in a downward direction. The cable 32 then extends completely across the top of both doors 28 and 38 in a strand 118 and is reeved around sheave 26 in an upward direction.

In the manner above described, cable 32 then is extended between sheaves 26 and 16, between sheaves 16 and 24, and between sheaves 24 and 14 in strands 120, 122 and 124. The cable 32 then extends from the bottom of sheave 14 to clamp 127 at the left side of the doors 28 and 30 where it is fixedly secured to the building structure 35 as shown. Cable 32 may be composed of strands of steel or in some door installations may be of rope or cord. In extremely heavy door installations part of the strands 116 and 118 of cable 32 may assume the form of a chain which may be driven by sheave 22.

Brackets 36, 38, 40 and 42 are provided as shown in FIGURE 1 to attach each of the separate door leaves 44, 46, 48 and 50 to the strands 122, 118, 116 and 112 respectively of cable 32. The brackets as shown are rigidly secured to the respective door leaves and are fixedly attached to the indicated cable strands in the position shown in the drawings to provide positive drive means for the individual leaves of the doors 28 and 30 during the opening and closing thereof.

The details of the brackets 36, 38, 40 and 42 are set forth in FIGURES 4 and 5. Each bracket consists of an L-shaped member 128 having a vertically extending leg 138 and a horizontal leg 132, a fiat plate 134 having three triangularly spaced threaded studs 135 extending from one side thereof and three annular disks 136. As shown the horizontal leg 132 of the L-shaped member 128 is adapted to be secured to the top edge of a door leaf by means of bolts 138. The vertically extending leg of the L-shaped member 128 is provided with triangularly spaced studs on the plate 134.

In assembly the cable 32 is attached to the brackets in the manner shown best in FIGURE 4. Disks 136 are sleeved over studs 135 on plate 134. The cable 32 is then wound around the annular disks 136 in the configuration shown in FIGURES 4 and 7 the studs 135 are then inserted within the triangularly spaced openings 137 in the vertical leg 130 of the L-shaped member 128. Lock washers 140 may then be placed over the ends of studs 135 and the studs 135 may be secured within the openings 137 and the circular disks 136 and plate 134 may be drawn tightly against the L-shaped member 128 by means of nuts 142 threadedly engaged with studs 135.

The disks 136 as shown are of slightly less thickness than the diameter of cable 32. Therefore, in the construction just described the cable 32 is securely gripped between the plate 134 and the vertically extending leg 130 of the L-shaped member 128 when the nuts 142 are drawn tight. The length of the vertically extending leg 130 of the L-shaped member 128 may be chosen to suit the relative elevation of the particular strands of cable 32 which it is desired to grip with the bracket. It will also be understood that the relative location of the brackets 36, 38, and 42 on the door leaves 44, 46, 48 and 50 may be varied to suit the conditions of the particular installation.

The drive means 34 for the door operating system of the invention as indicated best in FIGURE 1 includes a drive motor 144 which is capable of imparting both clockwise or counter-clockwise rotation to a driven sheave 146, and an endless belt 148 for transferring the relative rotation of the sheave 146 to a driving sheave 150 attached to shaft 104 for rotation therewith. As will subsequently be explained, clockwise rotation of sheave 146 and motor 144 will cause doors 28 and 30 to assume an open position. Subsequent counter-clockwise rotation of sheave 146 will cause doors 28 and 30 to assume a closed position substantially as shown in FIGURE 1. As shown the drive means 34 is located on the right side of the centrally divided doors 28 and 30 in a protected position at the top of the doors. It will be understood that other locations for the drive means 34 are possible.

As indicated above, clockwise rotation of motor 144 will cause sheave 146, sheave 150, shaft 104 and sheave 22 which is connected to shaft 104 for rotation therewith to also rotate in a clockwise direction. As sheave 22 is rotated in a clockwise direction the cable 32 is caused by frictional forces to move around sheave 22 in the direction indicated by the arrow heads on strands 116 and 118 of the cable 32. As will be evident from an inspection of FIGURE 1, movement of the cable 32 around the sheave 22 in a clockwise direction will tend to move the traveling sheave carriage 12 in a rightward direction as indicated by arrow 152. Movement of carriage 12 in the direction of arrow 152 will allow strands 110, 112, 114 and 116 of cable 32 to shorten.

For example, if the traveling sheave carriage 12 moves a distance to the right equal to one-half of the width of one of the door leaves each of the strands 110, 112, 114 and 116 of the cable 32 will be allowed to shorten an equal amount. A length of cable equal to the combined length of the shortening of these four strands of cable 32 will therefore be available to pass around sheave 22 in a clockwise direction during such movement of the carriage 12. The point on strand 116 of cable 32 to which bracket 40 is attached will therefore, be moved to the right four times the distance that the sheave carriage 12 moves to the right, that is, two full leaf widths. Since a length of cable equal to the combined length of the shortening of strands 110 and 112 of cable 32 on movement of carriage 12 will pass clockwise around sheave 21 with cable 32 mounted as shown, all points on strand 112 including the point at which bracket 42 is attached thereto must move to the right twice the distance that carriage 12 moves to the right or in the assembly illustrated one leaf width of doors 28 and 30.

It will be understood then that on clockwise rotation of sheave 22 that as sheave carriage 12 moves to the right one-half a leaf width that leaf 48 of door 30 will move to the right two full leaf widths and leaf 50 of door 30 will move to the right one full leaf width. At the end of this travel, leaves 48 and 50 will completely overlap each other and will be in the fully open position at the right side 31 of the opening 33 in the building structure 35.

In order for the sheave carriage 12 to advance toward the right in FIGURE 1, it will be understood that the strands 120, 122, 124 and 126 must be lengthened. Since the cable 32 is fixedly secured to the building structure at 127, the cable necessary to lengthen the strands 122, 120, 124 and 126 of cable 32 to permit carriage 12 to move to the right must be obtained due to the shortening of strands 11th, 112, 114 and 116 of cable 32 through the strand 118 of cable 32 extending between the driven sheave 22 at the right side of the doors 28 and 3t and the sheave 26 at the left side of the doors.

As previously stated a length of cable equal to two leaf widths of doors 28 and 30 will be allowed to pass over sheave 22 on horizontal movement of carriage 12 one-half leaf width. Since each of the strands 120, 122, 124 and 126' must be lengthened by one-half leaf width in order to allow the carriage 12 to move to the right one-half leaf Width, all points on strand 118 of cable 32 including that point at which the bracket 38 is attached thereto must move to the right two full leaves widths. Also, since each of strands 124 and 126 must be lengthened one-half leaf width, each point on strand 122 of cable 32 including the point at which bracket 36 is attached thereto must move to the right one full leaf width.

It will be seen then that as the carriage 12 moves to the right one-half a leaf width that the leaves 44 and 46 attached to the strands 122 and 1.18 of cable 32 respectively will move to the left one full leaf width and two full leaves widths respectively and assume an overlapping and completely open position. It will further be noted that the leaves 44 and 46 arrive at their fully open position at the same time that leaves 48 and 50 arrive at the fully open position and that during this time the traveling sheave carriage 12-has moved to the right one-half the width of one leaf of doors 28 and 30 due to clockwise rotation of sheave 22 by drive means 34.

In a similar manner, counterclockwise rotation of sheave 22 by drive means 34 will cause a shortening of the strands of cable 32 on the left side of the doors 28 and 30 and a similar lengthening of the strands of cable 32 on the right side of the doors 28 and 30 resulting in a movement to the left of carriage 12 of one-half of one leaf width to substantially the position shown in FIGURE 1. The individual leaves of doors 28 and 30 will on such movement to the left of the sheave carriage 12 assume the fully closed position illustrated in FIGURE 1 in a manner similar to that described above in which the leaves 46 and 43 travel twice the distance that leaves 44 and 50 travel in the same length of time.

While the particular embodiment of the invention described concerns double leaf centrally divided vertical doors sliding horizontally it will be appreciated that the invention herein disclosed may be applied to vertically sliding doors and to centrally divided sliding doors having more than two leaves. The applicant does not therefore wish to be limited in the practice of the disclosed invention to that embodiment thereof set forth in the drawings.

What I claim as my invention is:

1. An operating system for a door movable to fully closed and fully open positions respectively and having plural leaves simultaneously differentially movable to arrive simultaneously at fully closed and fully open positions, means for moving said door to fully closed and fully open positions by simultaneous differential movement of the leaves thereof including a first plurality of rotatable members and a second plurality of rotatable members fixedly mounted in spaced relation to each other, a carriage between said first and second pluralities of rotatable members movable in opposite directions along a predetermined path, third and fourth pluralities of rotatable members mounted on said carriage, a flexible linear member having anchored ends and a continuous section extending first from one of the anchored ends alternately and successively in reeved relation around separate rotatable members of said third and first pluralities respectively to form a plurality of pairs of portions of said section which extend from the carriage in one direction of carriage movement, said linear member having a second continuous section extending from a rotatable member of said first plurality alternately and successively in reeved relation around separate rotatable members of said second and fourth pluralities respectively, and finally from a rotatable member of said fourth plurality to the other of said anchored ends to form a plurality of pairs of portions of said second section which extend from the carriage in the opposite direction of carriage movement, movement of said linear member causing said carriage to move along its path and causing separate portions of said sections to move at different speeds in the same direction, means connecting the leaves of said door respectively to certain of the said separate portions, and means for moving said linear member in opposite directions to simultaneously differentially move the leaves of said door and thereby move said door to fully closed or fully open positions depending on the direction of movement of said linear member.

2. An operating system for a pair of doors movable toward and away from each other alon a predetermined path to fully closed and fully open positions respectively and each having plural leaves simultaneously differentially movable to arrive simultaneously at fully closed and fully open positions, means for simultaneously moving said doors toward and away from each other to fully closed and fully open positions by simultaneously differential movement of the leaves thereof including a first plurality of rotatable members and a second plurality of rotatable members fixedly mounted in spaced relation to each other, a carriage between said first and second pluralities of rotatable members movable in opposite directions along a predetermined path, third and fourth pluralities of rotatable members mounted on said carriage, a flexible linear member havinganchored ends and a first continuous section extending first from one of the anchored ends alternately and successively in reeved relation around separate rotatable members of said third and first pluralities respectively to form a plurality of pairs of portions of said section which extend from the carriage in one direction of carriage movement, said linear member having a second continuous section extending from a rotatable member of said first plurality alternately and successively in recved relation around separate rotatable members of said second and fourth pluralities respectively, and finally from a rotatable member of said fourth plurality to the other of said anchored ends to form a plurality of pairs of portions of said second section which extend from the carriage in the opposite direction of carriage movement, movement of said linear member causing said carriage to move along its path and causing separate portions of said first section to move at different speeds in one direction and separate portions of said second section to move at difierent speeds in the opposite direction, means connecting the leaves of one door respectively to said separate portions of said first section, -means connecting the leaves of the other door to said separate portions of said second section, and means for moving said linear member in opposite directions to simultaneously move the leaves of said doors and thereby move said doors to fully closed or fully open position depending on the direction of movement of said linear member.

References Cited in the ,file of this patent UNITED STATES PATENTS 678,422 Poulson July 16, 1901 1,658,640 Huberty Feb. 7, 1928 1,904,588 Weinberg Apr. 18, 1933 2,599,747 Craigon June 10, 1952 

1. AN OPERATING SYSTEM FOR A DOOR MOVABLE TO FULLY CLOSED AND FULLY OPEN POSITIONS RESPECTIVELY AND HAVING PLURAL LEAVES SIMULTANEOUSLY DIFFERENTIALLY MOVABLE TO ARRIVE SIMULTANEOUSLY AT FULLY CLOSED AND FULLY OPEN POSITIONS, MEANS FOR MOVING SAID DOOR TO FULLY CLOSED AND FULLY OPEN POSITIONS BY SIMULTANEOUS DIFFERENTIAL MOVEMENT OF THE LEAVES THEREOF INCLUDING A FIRST PLURALITY OF ROTATABLE MEMBERS AND A SECOND PLURALITY OF ROTATABLE MEMBERS FIXEDLY MOUNTED IN SPACED RELATION TO EACH OTHER, A CARRIAGE BETWEEN SAID FIRST AND SECOND PLURALITIES OF ROTATABLE MEMBERS MOVABLE IN OPPOSITE DIRECTIONS ALONG A PREDETERMINED PATH, THIRD AND FOURTH PLURALITIES OF ROTATABLE MEMBERS MOUNTED ON SAID CARRIAGE, A FLEXIBLE LINEAR MEMBER HAVING ANCHORED ENDS AND A CONTINUOUS SECTION EXTENDING FIRST FROM ONE OF THE ANCHORED ENDS ALTERNATELY AND SUCCESSIVELY IN REEVED RELATION AROUND SEPARATE ROTATABLE MEMBERS OF SAID THIRD AND FIRST PLURALITIES RESPECTIVELY TO FORM A PLURALITY OF PAIRS OF PORTIONS OF SAID SECTION WHICH EXTEND FROM THE CARRIAGE IN ONE DIRECTION OF CARRIAGE MOVEMENT, SAID LINEAR MEMBER HAVING A SECOND CONTINUOUS SECTION EXTENDING FROM A ROTATABLE MEMBER OF SAID FIRST PLURALITY ALTERNATELY AND SUCCESSIVELY IN REEVED RELATION AROUND SEPARATE ROTATABLE MEMBERS OF SAID SECOND AND FOURTH PLURALITIES RESPECTIVELY, AND FINALLY FROM A ROTATABLE MEMBER OF SAID FOURTH PLURALITY TO THE OTHER OF SAID ANCHORED ENDS TO FORM A PLURALITY OF PAIRS OF PORTIONS OF SAID SECOND SECTION WHICH EXTEND FROM THE CARRIAGE IN THE OPPOSITE DIRECTION OF CARRIAGE MOVEMENT, MOVEMENT OF SAID LINEAR MEMBER CAUSING SAID CARRIAGE TO MOVE ALONG ITS PATH AND CAUSING SEPARATE PORTIONS OF SAID SECTIONS TO MOVE AT DIFFERENT SPEEDS IN THE SAME DIRECTION, MEANS CONNECTING THE LEAVES OF SAID DOOR RESPECTIVELY TO CERTAIN OF THE SAID SEPARATE PORTIONS, AND MEANS FOR MOVING SAID LINEAR MEMBER IN OPPOSITE DIRECTIONS TO SIMULTANEOUSLY DIFFERENTIALLY MOVE THE LEAVES OF SAID DOOR AND THEREBY MOVE SAID DOOR TO FULLY CLOSED OR FULLY OPEN POSITIONS DEPENDING ON THE DIRECTION OF MOVEMENT OF SAID LINEAR MEMBER. 